Description:From a general study of the relations between models, meaning the set of variables with their mathematical properties, and the measures they represent, a new formalism is developed, which covers the scope of Quantum Mechanics. In this paper we prove that the states of any physical system can be represented in a Hilbert space, that a self-adjoint operator is associated to any observable, that the result of a measure must be an eigen value of the operator and appear with the usual probability law.